Information for controlling the use of content data such as dynamic image data and music data, for example, the number of times of copying and the number of times of viewing such content data, are relevant to copyright protection. Normally, such information is transferred in an encrypted state between devices in order to prevent falsification. However, a performance issue for data-storage devices, such as hard-disk drives (HDDs), has arisen because the load of operations for encryption and decryption of content data and the transfer of content data has increased. This performance issue has gained increasing attention as encryption and decryption has become more advanced and rigorous. Thus, engineers engaged in advanced HDD design for audio-video recording (AVR) have become increasingly interested in enabling HDD technology to meet the demands of the marketplace for HDD AVR applications.